1. Gary Eickmeier says:

    A most fascinating subject! Mythologically, a calendar based entirely on a religious figure who probably never even existed. Astronomically, the importance of keeping track of the motions of the planets and stars to know when the seasons arrive, for planting and other purposes. Technically, the importance of finding a watch accurate enough for navigation across the oceans for world exploration. Each of these areas is worth several volumes of study.